全文获取类型
收费全文 | 5142篇 |
免费 | 35篇 |
国内免费 | 33篇 |
专业分类
安全科学 | 59篇 |
废物处理 | 202篇 |
环保管理 | 198篇 |
综合类 | 2128篇 |
基础理论 | 931篇 |
环境理论 | 5篇 |
污染及防治 | 1136篇 |
评价与监测 | 346篇 |
社会与环境 | 186篇 |
灾害及防治 | 19篇 |
出版年
2023年 | 43篇 |
2022年 | 83篇 |
2021年 | 60篇 |
2020年 | 40篇 |
2019年 | 44篇 |
2018年 | 94篇 |
2017年 | 84篇 |
2016年 | 130篇 |
2015年 | 82篇 |
2014年 | 161篇 |
2013年 | 277篇 |
2012年 | 159篇 |
2011年 | 155篇 |
2010年 | 164篇 |
2009年 | 160篇 |
2008年 | 196篇 |
2007年 | 203篇 |
2006年 | 158篇 |
2005年 | 135篇 |
2004年 | 117篇 |
2003年 | 130篇 |
2002年 | 106篇 |
2001年 | 96篇 |
2000年 | 88篇 |
1999年 | 85篇 |
1998年 | 63篇 |
1997年 | 56篇 |
1996年 | 36篇 |
1995年 | 55篇 |
1994年 | 57篇 |
1991年 | 37篇 |
1990年 | 42篇 |
1989年 | 36篇 |
1985年 | 36篇 |
1979年 | 39篇 |
1969年 | 34篇 |
1967年 | 56篇 |
1966年 | 48篇 |
1965年 | 56篇 |
1964年 | 65篇 |
1963年 | 67篇 |
1962年 | 59篇 |
1961年 | 67篇 |
1960年 | 61篇 |
1959年 | 66篇 |
1958年 | 61篇 |
1957年 | 73篇 |
1956年 | 49篇 |
1955年 | 49篇 |
1954年 | 46篇 |
排序方式: 共有5210条查询结果,搜索用时 31 毫秒
21.
This study aimed at quantifying changes in urban area of the city of Kahramanmara? (K.Mara?) between 1948 and 2006, and analysing suitability of existing land use (LU) to the land potential. Urban change information was derived from two black-white monoscopic aerial photographs, and IKONOS and the QuickBird images acquired in 1948, 1985, 2000 and 2006, respectively. QuickBird image and soil map with 1:25,000 scale were used to analyze suitability of the current LU pattern to the land potential. The findings showed that the urban area of K.Mara? has expanded approximately 13 times during the past six decades. According to current LU and the soil map, productive and moderately productive soils were largely (73.2%) allocated for agricultural activities, which means that there was a strong consistency between the agricultural LU type and the land capability. However, widespread agriculture on the non-productive soils, and urbanization on the fertile agricultural lands were assessed as unsuitable from sustainable LU viewpoint. Considering this phenomenon, it is possible to say that rapid urban expansion has a growing pressure on the fertile agricultural soils. Monitoring LU changes, particularly urbanization, and developing effective LU plans based on the land capability were determined as the most important approaches to encourage sustainable use of land. 相似文献
22.
Schröder W Hornsmann I Pesch R Schmidt G Markert B Fränzle S Wünschmann S Heidenreich H 《Environmental monitoring and assessment》2007,133(1-3):495-505
The study was conducted to test the hypothesis that the regional variability of nitrogen (N) and metal accumulations in terrestrial ecosystems are due to historical and recent ways of landuse. To this end, two regions of Central Europe were selected for investigation: the Weser-Ems Region (WER) and the Euro Region Nissa (ERN). They were assumed to have land use-specific accumulation profiles. Thus, the metal and N accumulations in both regions were examined by means of geostatistically based comparative moss analysis. The sampling and chemical analysis of mosses were conducted in accordance with the convenient guidelines and methods, respectively. The spatial representativity of the sampling sites was computed by means of a land classification which was calculated for Europe by means of classification trees and GIS-techniques. The differences of deposition loads were tested for statistical significance with regard to time and space. The measurement values corroborated the decline of metal accumulation observed since the beginning of the European Metals in Mosses Surveys in 1990. The metal loads of the mosses in the ERN exceeded those in the WER significantly. The opposite holds true for the N concentrations: those in the WER were significantly higher than those in the ERN. The reduction of emissions from power plants, factories and houses was strongly correlated with the decline of deposition and bioaccumulation of metals. As proved by the European Metals in Mosses Surveys, this tendency is due to successful environmental policies. But no such success could be verified by monitoring the accumulation of N in mosses. 相似文献
23.
Martínez-Carballo E Sitka A González-Barreiro C Kreuzinger N Fürhacker M Scharf S Gans O 《Environmental pollution (Barking, Essex : 1987)》2007,145(2):489-496
A method for simultaneous quantitative determination of alkyl benzyl, dialkyl and trialkyl quaternary ammonium compounds (QACs) has been developed, validated and subsequently applied to real water samples in Austria. The method employs liquid-liquid extraction (LLE) followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS), using electrospray ionization (ESI) in positive mode. The overall method quantification limits range from 4 to 19ng/L for the enrichment of 500mL water samples and analyte recoveries are between 80 and 99%. The method was applied to 62 of the respective water samples without filtration to avoid the loss of the analytes due to the high adsorption capacity of these compounds. Maxima in the mg/L range, especially in the wastewater of hospitals and laundries, could be detected for the selected target compounds. 相似文献
24.
Use of USLE/GIS Methodology for Predicting Soil Loss in a Semiarid Agricultural Watershed 总被引:1,自引:0,他引:1
The Universal Soil Loss Equation (USLE) is an erosion model to estimate average soil loss that would generally result from
splash, sheet, and rill erosion from agricultural plots. Recently, use of USLE has been extended as a useful tool predicting
soil losses and planning control practices in agricultural watersheds by the effective integration of the GIS-based procedures
to estimate the factor values in a grid cell basis. This study was performed in the Kazan Watershed located in the central
Anatolia, Turkey, to predict soil erosion risk by the USLE/GIS methodology for planning conservation measures in the site.
Rain erosivity (R), soil erodibility (K), and cover management factor (C) values of the model were calculated from erosivity
map, soil map, and land use map of Turkey, respectively. R values were site-specifically corrected using DEM and climatic
data. The topographical and hydrological effects on the soil loss were characterized by LS factor evaluated by the flow accumulation
tool using DEM and watershed delineation techniques. From resulting soil loss map of the watershed, the magnitude of the soil
erosion was estimated in terms of the different soil units and land uses and the most erosion-prone areas where irreversible
soil losses occurred were reasonably located in the Kazan watershed. This could be very useful for deciding restoration practices
to control the soil erosion of the sites to be severely influenced. 相似文献
25.
The sonochemical degradation of the systematically substituted azo compound 2,7-dihydroxy-1-phenylazonaphthaline-3,6-disulfonic acid was investigated using a frequency of 850 kHz and an acoustic input power of 61 W. All derivatives were degraded completely within 6h by the ultrasonic treatment. Trifluoromethyl substituted azo compounds exhibited 2-3-fold higher degradation rates in comparison to the reference hydrogen substituted azo compound (k=0.54 h(-1)). In contrast to enzymatic processes (azoreductase or laccase), the ultrasonic treatment for these ortho-, meta-, and para-substituted azo compound showed 1.5-50-fold higher degradation rates. Additionally the ultrasound treatment was characterized by shorter reaction times. As a result of the detection and identification of specific intermediates using LC-MS a reaction pathway of the sonochemical degradation of the analysed azo compound is proposed indicating the formation of cyclohexadienone and naphthalene quinone derivatives. 相似文献
26.
BACKGROUND, AIM AND SCOPE: Conjoint analysis and the related choice-modelling methods have been used for many years in marketing research to evaluate consumer behaviour and preferences for different kinds of product attributes. Recently, the number of applications in environmental science and management has started to grow. Conjoint analysis is found in many different forms, and the environmental studies evaluated in this review display the same range of methods as in other fields. The key characteristic of all these methods is that trade-offs are evaluated by jointly considering a number of important attributes. MAIN FEATURES: This paper is a review of the literature on environmental applications of conjoint analysis and assesses in which environmental area conjoint analysis has been most successful. The method and the design of the studies are reviewed as well. RESULTS: A total of 84 studies were found, dealing with environmental issues that were evaluated by conjoint analysis. The studies concern agriculture, ecosystem management, energy, environmental evaluation, forestry, land management, pollution, products, recreation, environmental risk analysis and waste management. DISCUSSION: Choice experiments seem to have a comparatively stronger position in environmental studies than elsewhere. Most of the environmental applications are related to natural resource management. This is somewhat surprising, but a number of reports have appeared also on product evaluation, which could be a key application area in the future. CONCLUSIONS: Compared to marketing and transportation, the number of environmental conjoint studies is rather small but increasing, and the method has proven to work effectively in eliciting preferences on environmental issues. In environmental issues, experimenters often use choice experiments, especially concerning ecosystem management and environmental evaluations. When it comes to evaluating preferences concerning agriculture, forestry, energy and products, a more traditional approach of conjoint analysis is favoured. RECOMMENDATIONS AND PERSPECTIVES: Two new areas of application are identified in this review--environmental communication and expert elicitation. Conjoint analysis can thus be developed into a useful instrument for environmental risk analysis and communication, both of which are necessary for an efficient approach to risk governance. 相似文献
27.
28.
29.
The effect of ambient air pollution with increased ozone concentrations on the feeding behaviour of the beech weevil Rhynchaenus fagi L. was studied. In a dual choice feeding test the beech weevil preferred leaf disks from beech saplings exposed to ambient air against those from filtered air in 65.5% of all cases. 相似文献
30.
Dhaouadi Latifa Besser Houda Karbout Nissaf Khaldi Rabeb Haj-Amor Zied Maachia Sihem Ouassar Fatma 《Environment, Development and Sustainability》2022,24(9):10695-10727
Environment, Development and Sustainability - In dry-hot areas, such as southern Tunisia, the availability of good water is very limited by the low scanty rainfall, the long dry periods and the... 相似文献